“A substantial portion of the excess mortality among current smokers between 2000 and 2011 was due to associations with diseases that have not been formally established as caused by smoking,” concluded the authors of the study. “These associations should be investigated further and, when appropriate, taken into account when the mortality burden of smoking is investigated.

The research team analyzed information from five contemporary U.S. cohort studies, comprising data from 421,378 men and 532,651 women older than 55 years, and conducted a follow up review over 11 years. The relative risks were calculated according to the Cox proportional-hazards models, adjusted for...